To avoid the possibility theat it might soften and collapse, slip a stainless steel spring inside. That short is probably no prob, but can you slide a piece of pipe inside, nearly full length? That would be crush prooof.
So far, I've had more experience thinking than I've had brewing....you don't think they are mutually exclusive, do you?
72 batches so far,
48 wine, mostly Loquat, peach, plum, prickly pear
23 beers and ciders
1 Tequila, from a prickly pear wine experiment that didn't work. I call it "Prickly Heat"